Record Details

FORECASTING POTENTIAL DISTRIBUTION OF SPOT BLOTCH IN WHEAT UNDER CLIMATE CHANGE SCENARIO IN INDO-GANGETIC PLAINS

KrishiKosh

View Archive Info
 
 
Field Value
 
Title FORECASTING POTENTIAL DISTRIBUTION OF SPOT BLOTCH IN WHEAT UNDER CLIMATE CHANGE SCENARIO IN INDO-GANGETIC PLAINS
Ph.D.
 
Creator ALI VIANI
 
Contributor Parimal Sinha
 
Subject diseases, biological phenomena, wheats, planting, fungi, poultry equipment, inorganic compounds, area, climate, pathogens
 
Description Forecasting potential distribution of spot blotch in wheat under climate change scenario in Indo-Gangetic plains
Spot blotch (Bipolaris sorokiniana) in wheat is one of the most important diseases in warmer areas of the world particularly in South Asia. It has become a major production constraint in intensive rice-wheat cropping systems of Indo-Gangetic plains where around 12 million hectare wheat area is affected every year and yield losses in the tune of 20% to 80% were reported due to the disease. Spot blotch infection is reported to be highly influenced by weather factors mainly temperature and high relative humidity. However, little is known about the importance of small changes in temperature under field conditions either due to seasonal or global warming. The disease is increasingly becoming a cause of concern particularly in the warm and humid environments of Indian sub-continent. Forecasting of potential distribution under climate change requires a prior knowledge of the pathogen‟s response to the environmental conditions.
In the present study, criteria for spot blotch infection and developmental rate model have been worked out to explain spot blotch development in wheat under climate change scenario. Number of spot /cm2 leaf (infection index) has been measured in response to the main weather factors namely temperature and duration of relative humidity 95% or above (RH-duration) controlling the development of the pathogen. Temperature response was typically unimodal with cardinal temperatures, i.e. minimum, optimum and maximum, had been appropriated at 18, 29 and 34oC, respectively. Response of RH-duration was non-linear, which was characterized by a monotonic increase in infection index with the increase of RH-duration. For infection a temperature of 18-34°C with minimum 15 h of high RH was found to be required and defined as favorable period. Temperature response on incubation period has been estimated and incubation period model (IP20) for development of 20% spots from the start of infection. IP20 was decreased from 7 days at 18°C to 2 days at 29°C and afterward increased with the increase in temperature. Hourly rate of IP20 completion was best described as a linear increase in rate with increase of temperature up to approximately 29°C, then an exponential decline up to the maximum temperature of approximately 36°C in which disease development stopped. A model for hourly IP20
completion rate established as (0.002 Temp –0.03) {1 – exp [0.151(Temp – 36)]} could reasonably explain the rate of spot development for diurnal temperature fluctuations tested under natural infection in the field.
Elevated CO2 (450-550 ppm) exposure irrespective of temperature level in growth chamber has shown to increase in leaf area in wheat. Increase in spot size, infected area/cm2/leaf and decrease in incubation and latent period were noted under combined elevated CO2 and temperature (+1.5°C) level. Direct effect of temperature rise on pathogen growth rate and host and probably indirect effect of changes in host are contributing to increase in spot blotch development.
Impact of temperature rise on spot blotch favorable hours and rate for IP20 completion under current situation has indicated that eastern region of Indo-Gangetic plains is relatively more favorable during February-March than western region. Addition of temperature (1.5°C) above the ambient temperature has shown to increase favorable hours and rate of incubation period completion during February and March, however, proportion of increase in February was more than in March and western plains were shown to be more sensitive to temperature rise.
Current finding establishes the fact
 Occurrence of infection favorable temperature (18-34°C) and RH-duration (15 h or above) in crop canopy facilitates spot blotch infection and once infection takes place subsequent progress of the disease is largely dependent on temperature.
 Temperature response on incubation period could be used for prediction of first symptom appearance.
 Temperature rise is likely to escalate spot blotch infection throughout Indo-Gangetic plains as disease severity is likely to increase further due to availability of longer favorable hours as well as higher rate of incubation period completion.
A criterion for monitoring of infection favorable period and a developmental rate has been proposed to develop a spot blotch forecasting system for scheduling protective fungicide applications as the severity of the disease is likely to increase further under climate change scenario.
 
Date 2016-03-08T16:54:44Z
2016-03-08T16:54:44Z
2013
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/64954
 
Language en_US
 
Format application/pdf
 
Publisher IARI, Division of Plant Pathology,New Delhi